#include <iostream>
using std::cout;
using std::endl;

class C;

class A{
public:
    void print() const{
        cout << _a << endl;
    }

    void setC(C & rhs,int x);

    /* friend class B; */
private:
    int _a;
};

class B{
public:
    /* void setA(A & rhs,int x){ */
    /*     rhs._a = x; */
    /* } */
    friend class A;
private:
    int _b;
};

class C{
public:
    friend class B;
private:
    int _c;
};

void A::setC(C & rhs,int x)
{
        rhs._c = x;

}

void test0(){
    A a;
    B b;
    /* b.setA(a,100); */
    a.print();
}

int main(void){
    test0();
    return 0;
}
